Patent GB-639471-A (GB)
Title: Improvements in and relating to change-speed gears
IPC: F16H61/02
Filed: 1947-07-01
Abstract: 639,471. Change-speed control. SOC. ANON A. SAURER. July 1, 1947, No. 17350. Convention date, Sept. 16, 1946. [Class 80 (ii)] In a constant-mesh countershaft gear between aligned input and output shafts 14, 15, and having at least three wheelpairs (four shown), in which some changes in ratio require change of engagement of at least two frictionally synchronised balked dogclutches 18, 19, which may have conflicting synchronising requirements, e.g. one requiring acceleration, the other retardation, the drive through the gear during such a change is interrupted at at least one point, e.g. on the main and countershafts b y synchronised balked dog-clutches 30, 31, whereby the wheelpairs 1, 2; 3, 4 and 5, 6; 7, 8 controlled by the clutches 18, 19 are isolated from one another, permitting synchronism to be rapidly effected without mutual interference, after which drive is reestablished at the required point of interruption. Shift is by air-pressure, and the interrupter clutches 30, 31, which themselves share in ratio selection, are engaged under control of a valve 67 operated by the final engaging movement of the selector clutches 18, 19. The sequence of a shift involving change in all the clutches from the position shown, i.e. change-over of both double clutches 18, 19, disengaging the single interrupter-clutch 30 and engaging that 31, is as follows:-After setting a manually operated distributer-valve 64 to the position shown, the operator moves a lever 59 (having no other function described) 'to send air-pressure from a reservoir 55, through the distributer-valve 64 and conduits 71, 73 to the respective lower and upper faces of pistons 46, 67 which rock shafts 20, 21 for moving the double clutch 18 to the right and 19 to the left. At the same time pressure from a branch-line 63 passes through a groove 85 in a piston-valve 67 and a conduit 80, to the respective lower and upper faces of coaxial pistons 48, 49, the latter, 49, of which remains in the lower position, whilst the former, 48, moves upwards, rocking a shaft 36 to disengage the interrupter-clutch 30. The two wheel-pairs 1 - 4 and 5 - 8 on opposite sides of the interrupter-clutch 30 are now isolated from each other and their dog-clutches 18, 19 make rapid synchronous mesh, conclusion of which causes one shift-piston 47 to uncover a central port 100 sending air-pressure through a conduit 98 to raise a spring loaded interlock valve-piston 96, permitting pressure to be sent from a central port 99, uncovered by the other shift-piston 46, through a conduit 93 and valve groove 95, to shift the spring-loaded piston-valve 67 to the right, venting the conduit 80 and directing pressure through a valve-groove 86, conduit 78, distributer-valve 64 and conduit 75, to the lower face of the interrupter-clutch piston 49, which thus moves upwards, rocking a shaft 37 to engage the countershaft interrupter-clutch 31, restoring the drive and completing the shift. The interrupter-clutches 30, 31 are interlocked by a sliding extension 54 of the upper piston-rod 44, which, in the position shown, abuts on the lower piston 49 and so prevents simultaneous engagement of both interrupter-clutches 30, 31, but permits simultaneous disengagement.